1. Field of the Invention
The present invention relates to a method and apparatus for changing railway sleepers, and in particular, to a method and apparatus for simultaneously lifting rails and unfastening sleepers, removing the sleepers, and installing replacement sleepers.
2. Description of the Related Art
Sleepers used to support rails are usually made of wood or concrete. Wooden sleepers must be replaced typically at regular intervals. Conventionally, rails first have to be unfastened from the sleepers, and thereafter, the sleepers are pulled out from under the rails. Then, new sleepers are pushed forcibly under the rails by using a machine for changing sleepers and then are fastened to the rails. Concrete sleepers are changed when basic repairs done to the railway line are completed or when track gauge is changed. When the sleepers are replaced by conventional methods, however, sections of a railway network must be closed to traffic. Moreover, conventional replacement equipment is large, complex, and cumbersome. Also, even when working with small scale equipment trains cannot run on the line, and thus, the equipment must be removed to let the trains run. This process takes a lot of time moving the machines away from the lines and putting them back on again.